The invention refers to a device for fracture fixation. Devices for fracture fixation are known from EP 0 698 800, which discloses affixing an elongated rod on the bone. Further, documents GB 2 268 068 and DE 923 085 disclose devices for fracture fixation comprising at least a deformable element and compression means to apply a compression force to the deformable element, so the deformable element deforms laterally.
Each of the well established fixation methods (rigid compression planting, reamed intramedullary nailing, with or without interlocking of the fracture fragments, external fixation and dynamic hip screw) has advantages and disadvantages as well as special biomechanical characteristics. Vast clinical experience combined with the data produced from theoretical and experimental studies have described many of the problems related to the biomechanics of these fracture fixation devices.
Today's understanding of bone biology has led us to a new approach to bone fixation. This approach considers the importance of the preservation of the soft tissue and of careful protection of the viability of bone. This invention aims to add to the theory and practice of bone fixation the concept that the fracture fixation device introduces into the broken bone equilibrium tensions to restore the intraosseous forces and make the bone capable of receiving the load stresses and muscle-spasm stresses right at the beginning of the healing period, as opposed to the prior concept that it is the device that receives these stresses.
A first attempt towards these goals is disclosed by Protogirou in PCT International Publication Number WO 91/19461 (title: Device for Osteosynthesis with Axially Guided Prestressing Elements). This device was also trying to solve some of the problems related to the biomechanics of bone fixation using axial prestressing to achieve stable and elastic osteosynthesis thus restoring the intraosseous forces. The resetting of the fragments remains stable by the medullary guide and the axial prestressing is applied through the tendons.